Furnace-regulator system



Mar. 27, 1923. 1,449,882. 0. A. BODDIE.

FURNACE REGULATOR SYSTEM. FILED JUNE 25, 1919.

WITNESSES:

INVENTOR Patented Mar. 27, 1.923.

UNITED STATES PATENT -OFFICE.,.

CLARENCE A. BODDIE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB TO HOUSE ELECTRIC 6; MANUFACTURING COMPANY, A. CORPORATION OF PENN- SYLVAN'IA.

FURNACE-REGULATOR SYSTEM.-

Application flled June 25, 1919. Serial No. 306,726;

To all whom it may concern:

Be it known that I, CLAREKCE A. BODDIE, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Furnace-Regulator Systems, of which the following is a specification. 7

My invention relates to regulator systems and particularly to systems for governing the operation of the movable electrodes in electric furnaces.

One object of my invention is to provide a furnace-regulator system that shall so operate the movable electrodes as to maintain a substantially-constant electrode arc and insure against hunting action.

In an electric furnace of the movable-electrode type, it is necessary to keep adjusting each electrode, relative to the bath of material being treated, in order to maintain the power supplied to the furnace substantially constant. Such adjustment ofthe electrode by hand is impractical, inasmuch as it requires the constant attention of an operator and, moreover, it is diflicult to obtain satisfactory or close regulation of a furnace by such method.

Heretofore, the regulation or adjustment of the movable electrode has been-accomplish'edl'by means of a regulator which was operated in accordance with the current flowing through the furnace, or in accordance with the voltage obtained between the movable electrode and the bath of material being treated. However, such operation has proved defective in many cases by reason of the failure to provide reliable and effective means of preventing hunting action by the regulator. t

In a furnace-regulator system constructed in accordance with my invention, the movable electrode is raised and lowered, relative to the'bath of material being treated, by

. means of an electric motor which is govoperationof the electrode motor in a clock- W186 and in a counterclockwise direction for lowering and raising the electrode, comcomprises a main-control electromagnet and electrode. One of said switches is provided I with an interlock switch member for connecting a resistor in shunt to one portion of said electromagnet winding in order to prevent hunting action wlienthe motor is being rotated in a counterclockwise direction to reduce the. current fiow through the electrode. The second switch is provided with an interlock-switch member for connecting the second section of the electromagnet winding in shunt to a second resistor that is normally in series with the first winding section. The second interlock-switch member and the second resistor serve to prevent any hunting action by theregulator when themotor is beingoperated in a-clockwise direction to lower the electrode and to increase the current flow throu h it. The 'two switches are further provide with interlock-switch members for establishing a brake circuit through the electrode motor upon-release of them.

The single figure in the accompanying drawing is a diagrammatic view of a regulator system embodying my Invention.

Referring to the drawing, an electric furnace 1, comprising a receptacle 2 containing a bath of material 3-, and three movable elec trodes 4, 5 and 6. is directly connected to a three-phase supply circuit comprising conductors 7 8 and 9.

A motor is-provided for raising and lowering each of the electrodes 4, 5 and 6, and .a regulator is provided for each motor in order to control the motor in accordance with the current flowing through the associated electrode. Inasmuch as the motors as- .tors are similar in construction and operation, it is deemed sufiicient to illustrate and describe only one regulator and the operation of one motor and one electrode by such re ulator.

he electrode 6 is provided with a motor 10 for raising and lowering it, and a regulator 11 for governing the operation of the motor. 10 in accordance with the current flowing through the electrode. The motor 10 comprises an armature l2 and a field winding 13 which is directly connected across the supply circuit comprising conductors l4 and 15. The armature 12 of the motor 10 is mechanically connected to the electrode 6 in any suitable manner, as by means of a shaft 16, a winding drum 17, and a flexible connector 18 which. passes over a pulley 19'. The regulator 11 comprises a ma1n control electromagnet 20, a switch 21, which is operated by the electiomagnet 20 .for effecting rotation of the motor 10 in a counterclockwise direction, and a switch 22 which is operated by the electromagnet 20 for efi'ecting clockwise rotation of the motor 10. The electromagnet 20 comprises a winding 23 which is divided into two sections 23 and 23 and a core armature 24 which is pivotally connected to a contact arm 25. The winding 23 is connected to the threephase supply conductor 9 by means of a current transformer 26 in order to operate the electromagnet in accordance with the current flowing through the electrode 6. The core armature 24 is provided with a dash-pot 27 for adjusting the speed of its operation. A tap, which isjoined to the winding 23 at the point of connection of the two sections 23 and 23", is directly connected to two resistors 28 and 29, for completing circuits, in a manner to be hereinafter set forth, to prevent hunting action. The contact arm 25 is pivotally mounted at 30 and is provided with two main contact. members 31 and 32, which are mounted on: the end of the contact arm 25 opposite to the end connected to the core armature 24. The contact member 31 engages a main contact member 33, in one position of the contact arm, in order to increase the curture 37. The core armature 37 operates two switch members 38 and 39, and two interlock-switch members 40 and 41. The switch members 38 and 39 connect the armature 12 across the supply conductors 14 and 15 for effecting rotation of the motor 10 in a counterclockwise direction to raise the electrode 6 from the bath of material 3. The interlock-switch member 40 serves to connect the resistor 29 in shunt to the electromagnet winding section 23, for changing the setting of the regulator, upon operation of the switch 21, to prevent hunting action by the regulator when-the electrode is being raised.

The switch 22 comprises a winding 42,

which is connected across the supply conductors 14 and 15 upon engagement of the contact members 31 and 33, and a core ar- .mature 43 which operates two contact members 44 and 45 and two interlock-switch members, 46 and 47. The switch members 44 and'45 connectthe armature 12 across I action by the regulator when the motor is operated in a clockwise direction to lower the electrode 6.

The interlock-switch members 41- and 47 complete a circuit through a brake-relay 50 from the supply conductors 14 and 15 upon de-energization of the switches 21 and '22. The relay 50 completes adyn'an'iic-braking circuit for the armature 12 through a resistor 51. When the motor 10 is -operated, either in a counterclockwise direction or in a clockwise direction, the releasing of either the switch 22 or the switch 21 operates the brake magnet 50 for completing the dymimic-braking circuit to eifect a quick stopping of the motor 10. I

Assuming the apparatus of the system to be in the position shown in the drawing and a current below normal amount to flow through the,electrode 6, then a decreased current flows through the winding section 23 of the electromagnet 20 to operate the contact arm 25 and effect engagement between the contact members 31 and 33. In this regard, it should be noted that the circuit of the winding section, 23 is completed through the resistor 28, and the winding section 23 and the resistor 29'are excludedfrom circuit. Upon engagementv of the contact members 31 and 33, a circuit is completed, from the supply conductor 14, through the contact arm 25, the contact 31 and 33, and the winding 42, to the supply conductor 15. .Thereu n, the switch 22 is operated for rotating t 0 motor 10 in a clockwise direction to lower the electrode6 and increase the current flow through it.

If the regulator 11 were controlled solely by the current flowing through the electrode 6 for stopping the operation of the motor 10, the main control magnet 20 wouldnot be operated to disconnect the contact members 31 and 33 to" release the switch 22 and stop the motor 10 until normal current conditions were obtained in the electrode circuit. Consequently,by reason of the inertia of the various moving parts of the regulator, it is seen that the motor 10 would overtravel to lower the electrode 6 beyond the determined pointand, accordingly, to increase the cur rent flow through the electrode above a normal amount. In order to prevent such overtravel and the resulting so-called huntlng action, the interlock switch member 46 is. operated simultaneously with the energ1za-- tion of the motor 10 to connect the winding section 23 'of the electromagnet 20 in shunt to the resistor 28. Thus, the setting of the regulator is changed and the contact arm 25 is operated to separate the contact members 31 and 33 just prior to the obtaining of normal current flow through the electrode 6.

In case the current flow through the electrode 6 is above normal amount, the electromagnet 20 operates the contact arm 25 to effect engagement between the contact members 32 and 34. Upon engagement of the contact members 32 and 34, a circuit is completed from the supply conductor 14 through the contact arm 25, the contact members 32 and-34, and the winding 36 to the supply conductor 15. Thereupon, the switch 21 1s operated for effecting rotation of the motor 10 in a counterclockwise direction to raise the electrode 6 and decrease the current flow through it. Y

In order to prevent hunting action .by the regulator when the motor is operating in a counterclockwise direction, the interlockswitch member 40 is operated simultaneously with the energization of the motor 10 to connect the resistor 28 in shunt to the winding section 23 of the electromagnet 20. Thus,

the setting of the regulator is changed to effect separation of the contact members 32 and 34 just prior to the obtaining of normal current flow through the electrode 6.

From the. above description, it is apparent.

' that not only the number of effected turns of the winding 23 of the electromagnet 20 is varied, but also the resistance of the electro magnetic circuit is varied in orderto prehunting action-when the elecvent' anie trode is ing raised and lowered.

Modifications in the system and arrangement and location of parts may be made with-v in the spirit and scope of my invention, and such modifications are intended to be covered by the appended claims.

I claim as my invention:

1. In a furnace-regulator system, the combination comprising a movable electrode, means for raising and lowering the electrode, and a regulator for governing the operation of said means, said regulator comprising an electromagnet operated in accordance with the condition of the electrode circuit, and.

magnet winding and for varying the resistance of the magnet circuit to prevent hunting action.- I

3. In a furnace-regulator system, a movable electrode,fand means comprising a regulator for overning the operation of the electrode, said regulator comprising an elec-' tromagnet energized in accordance with the electrical condition of the electrode circuit and means for varying the number of effective turns in the magnet winding and for varying the resistance of the magnet circuit to prevent hunting action.

4.- In .a furnace-regulator system, a movable electrode and means comprising a regulator for governing the operation of the electrode, said regulator comprising an electromagnet energized in accordance with the current flowing through the electrode and means comprising two resistors for varying the electromagnet circuit to prevent hunting action by the regulator.

5. In a'furnace-regulator system, a movable electrode, a motor for raising and lowering the electrode, and a regulator for governing the operation of said motor, said regulator comprising an electromagnet and means for varying the residzance of the magnet circuit to prevent hunting action whelnthe electrode is being ,raised and lowere 1 -6.- In a furnace-regulator system, the combination with a movable electrode and means for raising and lowering the electrode, of a re ulator for governing the operation of said means and comprising an electromagnet operated in accordance with the current flowing through the electrode,

a resistor for shuntingone portion. of the magnet winding to prevent hunting actlon when the electrode is being raised,

and a second resistor for shunting another portion of the winding of said magnet to prevent hunting action when the electrode is bein raised. 4

7. In a urnace-regulator system, the combination comprising a movable electrode, a motor for raising and lowering said electrode, and a regulator for governing the operation of said motor to maintain a constant electrode are, said regulator comprising an electromagnet operated in accordance with the current flowing throughthe electrode and resistors for short-circuiting portions of the winding of the electromagnet to prevent hunting action.

8. In a furnace-regulator system, a plurality of movable electrodes, and a regulator for governing the operation of each of said electrodes, each of said regulators comprising an electromagnet energized in accordance with the current flowing through the associated electrode and means for simultaneously varying the number of effective' turns in the magnet winding and the resistance of the magnet circuit to prevent hunting action by the regulator.

9. In a furnace-regulator system, the combination with a movable electrode, and a motor for raising and lowering said electrode, of a regulator for governing the operation of said motor to maintain a constant electrode arc, said regulator comprising an electromagnet having a winding divided into two sections and operated in accordance with the current flowing through the electrode, two resistors, a' switch for connecting one resistor in shunt to one of said winding sections to prevent any hunting action during one operation of the electrode, and a second switch for connecting the second resistor in shunt to the second section of the magnet winding to prevent hunting action during another operation of the electrode.

10. In a furnace-regulator system, the combination with a movable electrode and a motor for raising and lowering said electrode, of a regulator for governing the operation of said motor to maintain a constant electrode arc, said regulator comprising an electromagnet having a winding divided into sections and energized in accordance with the current flowing through the electrode, two resistors, means for connecting one resistor in shunt to one section of said winding and the second resistor in series with said section to prevent hunting action when the electrode is being raised, and means for connecting the resistors severally in shunt I to the two sections of said winding when the electrode is being lowered.

11. In a regulator system, a supply circuit, a resistance-varying means in sald cirelectromagnet operated in accordance with the condition of the supply circuit, resistance elements in circuit therewith and means for varying the number of effective turns in the magnet winding and also forvarying the resistance of the magnet circuit to prevent hunting action.

13. In a regulator system, a supply circuit, resistance-varying means in said supply circuit, a regulator for varying the operation of said means in accordance with supply-circuit conditions, said regulator comprising an electromagnet, and "means for varying the external resistance of the magnet circuit to prevent hunting action.

14. In a regulator system, a supply circuit,

a resistance-varying means connected to said circuit and means comprising a regulator for governing the operation of said means, said regulator comprising an electromagnet energized in accordance with the current flowing through the supply circuit and means comprising two resistors for varying the electromagnet circuit to prevent hunting action by the regulator.

15. In a furnace-regulator system, the combination comprising a movable electrode, a motor for raising and lowering the electrode, means comprising an electromagnet for governing the operation of said motor, and means for varying the circuit of said magnet to change its setting when the electrode is being raised or lowered.

16. In a regulator system, the combination comprising a supply circuit, resistance-varying means in said supply circuit, means comprising a magnet for varying said resistancevarymg means in accordance with supplycn'cuit conditions, an impedance device in circuit with said magnet and means for varying the value of said impedance device in the magnet circuit. 7

In testimony whereof, I have hereunto sglligcribed my name this 20th day of June,

CLARENCE A. BODDIE. 

